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Search for "structure" in Full Text gives 2869 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Wittig reaction of cyclobisbiphenylenecarbonyl
Beilstein J. Org. Chem. 2025, 21, 1454–1461, doi:10.3762/bjoc.21.107
- formation between carbonyl and alkene units. Keywords: bathtub; chirality; cyclobisbiphenylenecarbonyl; figure-eight; Wittig reaction; Introduction Figure-eight π-conjugated molecules represent chiral macrocycles with a twisted crossover structure [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15
- ]. Various figure-eight π-systems including aromatic hydrocarbons, belt-type extended π-systems, and porphyrinoids have been reported. The structural twisting in figure-eight macrocycles leads to cross-linked conjugation at the molecular center and a highly symmetric chiral structure with D2-symmetry
- stable figure-eight conformation A to a metastable bathtub conformation B with a small energy difference of approximately 2 kcal mol–1 [21]. In this paper, we discuss the effect of the transformation of the carbonyl groups on the conformational change of the figure-eight structure. We thus intentionally
Advances in nitrogen-containing helicenes: synthesis, chiroptical properties, and optoelectronic applications
Beilstein J. Org. Chem. 2025, 21, 1422–1453, doi:10.3762/bjoc.21.106
- helicenes. Particular attention is given to multi-heteroatom systems co-doped with elements such as boron, oxygen, sulfur, and selenium, highlighting their influence on CPL performance and structure–property relationships. We classify the nitrogen-doped helicenes into only N-containing helicenes, B,N
Tautomerism and switching in 7-hydroxy-8-(azophenyl)quinoline and similar compounds
Beilstein J. Org. Chem. 2025, 21, 1404–1421, doi:10.3762/bjoc.21.105
- substitution in 7-OH quinoline, where the most of the requirements for clean switching are achieved if the K tautomer is considered as off-state and the E one as on-state. Experimental Synthesis and structure elucidation Materials The starting reagents and solvents were purchased from Sigma-Aldrich and
- M06-2X [96][97] functional with the TZVP [98] basis set was used for the structure optimizations in the ground state. The use of M06-2X provides very good predictability in the ground state [51][53][99][100][101][102][103] of the tautomeric composition in tautomeric compounds and proton cranes as well
Reactions of acryl thioamides with iminoiodinanes as a one-step synthesis of N-sulfonyl-2,3-dihydro-1,2-thiazoles
Beilstein J. Org. Chem. 2025, 21, 1397–1403, doi:10.3762/bjoc.21.104
- analogy with an aza-Michael reaction first with the addition of iminoiodinane accompanied with reorganization of double bonds including attack of the negatively charged sulfur atom on nitrogen with subsequent elimination of iodobenzene as good leaving group. The diversity of the structure of the target
- 2,3-dihydro-1,2-thiazole ring are in the range of 75.3–72.4 ppm and signals of the carbon atom of the cyano group in the range of 117.7–116.6 ppm. The structure of 2,3-dihydro-1,2-thiazole 3aa was additionally confirmed by single crystal X-ray diffraction (Figure 2). According to the X-ray diffraction
- (1.5 mL) was added dropwise. The reaction vessel was removed from the ice bath and the reaction mass was stirred for 10–30 min, then transferred to a silica gel column and the corresponding 2-sulfonyl-1,3-thiazole 3 was isolated. X-ray structure determination of 3aa. Crystal data for C21H21N3O3S2 (M
N-Salicyl-amino acid derivatives with antiparasitic activity from Pseudomonas sp. UIAU-6B
Beilstein J. Org. Chem. 2025, 21, 1388–1396, doi:10.3762/bjoc.21.103
- human system. In this study, we isolated two previously undescribed N-salicyl-amino acids as natural products (1 and 2) and other two new derivatives (3 and 4) from the organic extract of a culture broth in a modified starch–glucose–glycerol (SGG) medium of Pseudomonas sp. UIAU-6B. The structure of the
- to C-10 showing the presence of the carboxyl functionality of the threonine moiety. Based on this conclusion, the structure of 1 was elucidated and named pseudomonin D. Compound 2 was obtained as a reddish oil, and the molecular formula deduced as C16H20N4O4 (Δ: +0.4 ppm, calcd. for C16H21N4O4
- Supporting Information File 1, Figure S16) confirming that both of these protons were present on the same side of the double bond. The structure of 3 was confirmed using mass spectrometry, 1D and 2D NMR data as a new compound, named pseudomonin F. Compound 4 was isolated as a pink oil. The negative mode
Oxetanes: formation, reactivity and total syntheses of natural products
Beilstein J. Org. Chem. 2025, 21, 1324–1373, doi:10.3762/bjoc.21.101
- substrate scope revealed that the reaction stereoselectivity is highly dependent on the structure of the ketoester component and tends to be unpredictable. 1.3.2 Formal cycloadditions: These stepwise processes typically take place between an enolate or enol ether and a carbonyl under Lewis acid or base
Recent advances and future challenges in the bottom-up synthesis of azulene-embedded nanographenes
Beilstein J. Org. Chem. 2025, 21, 1272–1305, doi:10.3762/bjoc.21.99
- ], medicine [3], sensing [4] and energy storage [5]. Typically, bulk graphene is obtained using a top-down approach, where graphite is exfoliated using chemical or mechanical methods [6][7]. However, this method does not provide precise control over the structure of graphene and graphenoid materials, which is
- crucial for fine-tuning their properties. An alternative is the bottom-up approach where various nanographenes are synthesized form smaller building blocks via classical organic synthesis. This strategy enables precise control over the structure and topology, leading to the development of a vast array of
- benzenoid nanographenes, also known as polycyclic aromatic hydrocarbons (PAHs) [8][9]. PAHs can be considered molecular models of bulk graphene, offering invaluable insights into structure–property relationships in graphene and graphene-based materials. Structural defects appear to be inevitable in real
Selective monoformylation of naphthalene-fused propellanes for methylene-alternating copolymers
Beilstein J. Org. Chem. 2025, 21, 1183–1191, doi:10.3762/bjoc.21.95
- % probably owing to the network structure. By contrast, soluble [3.3.3]_oligo and [3.3.3]_linear had relatively high T90 of 528–532 °C and CY of 68–76 wt %. The high values were ascribed to two unsubstituted naphthalene rings in precursor [3.3.3]_CH2OH, which caused facile branching in the reaction or
Enhancing chemical synthesis planning: automated quantum mechanics-based regioselectivity prediction for C–H activation with directing groups
Beilstein J. Org. Chem. 2025, 21, 1171–1182, doi:10.3762/bjoc.21.94
- structure on the potential energy surface is located, which can be done straightforwardly using standard optimization algorithms. While the use of intermediate energies provides a computationally efficient alternative to explicit transition state searches, it rests on the assumption that there is a
- the transition state [10][11]. The site with the lowest reaction energy is expected to correspond to the experimentally observed reaction site. Therefore, instead of locating the structure of the transition state, the preceding palladacycle intermediate structure is generated and optimized, as shown
- carbon at the reaction site and to the heteroatom of the directing group, as illustrated in Figure 5. To assess the geometry of these complexes, we generate a 2D structure using RDKit, where all atoms are constrained to lie in a single plane. Although this type of 2D embedding is typically used only for
A multicomponent reaction-initiated synthesis of imidazopyridine-fused isoquinolinones
Beilstein J. Org. Chem. 2025, 21, 1161–1169, doi:10.3762/bjoc.21.92
- , Supporting Information File 1), but it was not stable enough for isolation. The structure of 8a was confirmed by single crystal X-ray diffraction analysis. The optimized reaction conditions were used to evaluate the substrate scope of the synthesis of imidazopyridine-fused isoquinolinones 8 (Scheme 3). The
- the dienophile presents a negative charge (−0.280 to −0.325, 6a), (−0.280 to −0.327, 6h) and (−0.280 to −0.327, 6r), respectively. This structure induces electrostatic repulsion instead of the requisite attraction for a successful interaction between the electron-rich diene and the electron-deficient
- detected by LC–MS from the reaction mixture. The X-ray structure of 6t indicated that the diene and dienophile are perpendicular to each other which prevents them from being properly aligned for the IMDA reaction. The transition state of the IMDA is electronically destabilized by the sulfur group of the
Synthetic approach to borrelidin fragments: focus on key intermediates
Beilstein J. Org. Chem. 2025, 21, 1135–1160, doi:10.3762/bjoc.21.91
- a cancer therapeutic, exhibiting anti-inflammatory, anti-angiogenic, antimicrobial, antifungal, and antimalarial activities. While Keller-Schierlein first determined its chemical structure, Anderson later confirmed its absolute configuration using X-ray crystallography [16]. During the screening of
- complex structure, remains an attractive target for synthetic organic chemists worldwide. Several comprehensive reviews on borrelidin have been published, with a strong focus on its synthesis. The first notable comparison of total synthesis methods was conducted by Ōmura in 2005 [48], highlighting four
- LiAlH4 in ether to form alcohol 40 (89%) (Scheme 3). The primary alcohol 40 was then converted to its iodide derivative 42 (89%), from which single crystals were obtained, and its structure was determined unequivocally by XRD crystallography. Iodide 42 was then reacted with sodium phenylsulfinate in DMF
Investigations of amination reactions on an antimalarial 1,2,4-triazolo[4,3-a]pyrazine scaffold
Beilstein J. Org. Chem. 2025, 21, 1126–1134, doi:10.3762/bjoc.21.90
- HMBC spectrum of 2 allowed unambiguous assignment of the amine substitution at C-8 with the amine proton (δH 8.30) showing strong HMBC correlations into the triazolopyrazine scaffold [δC 147.9 (C-8), 139.7 (C-9)]. 2D NMR correlations used to characterise the structure of 2 are shown in Figure 2, along
- with relevant position numbering. Crystals obtained for 2 were analysed by X-ray crystallographic studies and confirmed the NMR-based structure assignment. The crystal structure of 2 is shown as a thermal ellipsoid plot below (Figure 3). With a simplified approach for the synthesis of aminated
Gold extraction at the molecular level using α- and β-cyclodextrins
Beilstein J. Org. Chem. 2025, 21, 1116–1125, doi:10.3762/bjoc.21.89
- stripping from activated carbon using α-cyclodextrin. J. Am. Chem. Soc. 2021, 143, 1984–1992. Copyright 2020 American Chemical Society. This content is not subject to CC BY 4.0. Solid-state structure of the complex 2β-CD·HAuBr4·DBC. (a) Capped-stick and space-filling representation of different views of 2β
A versatile route towards 6-arylpipecolic acids
Beilstein J. Org. Chem. 2025, 21, 1104–1115, doi:10.3762/bjoc.21.88
- . It contains a six-membered ring and is, like its five-membered correlate, known for its secondary structure inducing properties, which are particularly useful in the design of peptide conformations. We present a new and improved way to generate enantiomerically pure pipecolic acid derivatives with
- structure of pipecolic acid is rather challenging and often necessitates early-stage derivatization followed by the formation of the six-membered ring [29][30][31][32]. An alternative is to utilise derivatization reactions such as Suzuki–Miyaura [33] or Sonogashira–Hagihara [34] cross-coupling reactions on
- the Sonogashira–Hagihara cross-coupling products [35]. Furthermore, an in-depth NMR analysis was conducted on the resulting constraints leading to conformational structure predictions. ᴅ-2-Aminoadipic acid (1) [36], a side product formed in the pharmaceutical semisynthesis of 7-aminocephalosporanic
Supramolecular assembly of hypervalent iodine macrocycles and alkali metals
Beilstein J. Org. Chem. 2025, 21, 1095–1103, doi:10.3762/bjoc.21.87
- pattern of assembly between HIM and metal cation in 2:1 ratio. While association with sodium leads to a polymer-like network, the lithium crystal structure was limited to dimeric assemblies of HIM. In the lithium-coordinating complex, the oxygen–lithium–oxygen bond angle is approximately 98.83
- durability, low harmful, and convenient alternative to heavy-metal reagents [10][11]. Hypervalent iodine compounds exist as trivalent (λ3-iodanes) or pentavalent (λ5-iodanes) species. The λ3-iodanes have an T-shaped structure [12], with the energetically preferred arrangement of the two most electronegative
- projecting outward denoted by an asterisk. Furthermore, the resulting crystal structure reveals that 1 is also a distorted planar macrocyclic system consisting of the amino acids carbonyl oxygens facing inside the ring. All three benzyl groups are located above a single plane (more figures are provided in
Biobased carbon dots as photoreductants – an investigation by using triarylsulfonium salts
Beilstein J. Org. Chem. 2025, 21, 1024–1030, doi:10.3762/bjoc.21.84
- ; the first one involves the direct carbonization (at 200–400 °C) of the precursor material for 24–100 hours under solvent-free conditions. The obtained carbon nanomaterials exhibit predominantly a graphitic core structure. In contrast, under hydrothermal conditions, the starting substrates were
- dissolved or suspended in water, and the resulting mixture transferred to an autoclave and treated at a temperature ranging 140–200 °C; the treatment yields CDs with an amorphous structure. The synthetic procedure, as well as the structural and morphological characteristics of these materials, have been
- previously reported by the research group of M. Selva and A. Perosa (see also Supporting Information File 1 for further details) [30][31][32][33][34][35]. As shown in Table 1, the materials synthesized via pyrolysis exhibit a graphitic core, characterized by an ordered structure, whereas those synthesized
Recent total synthesis of natural products leveraging a strategy of enamide cyclization
Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81
- , lycopodine features a characteristic tetracyclic structure with a bridged cyclohexanone. To address the challenges associated with constructing the complex ring systems of this structure, She and co-workers devised an intramolecular aza-Prins cyclization strategy to form both the bridge ring and the N-hetero
- [2,1-a]isoquinolin-3(2H)-one framework is a pivotal core structure among various pyrrolo[2,1-a]isoquinoline alkaloids, exemplified by (+)-crispine, annosqualine, and erysotramidine, among others (Scheme 5) [29]. These bioactive alkaloids exhibit a broad spectrum of biological activities, including
- notable example is (−)-cephalocyclidin A, a cytotoxic pentacyclic cephalotaxus alkaloid [33][34]. Although the molecular structure contains a benzo-bridge ring system, disconnection of this bridge reveals a critical tricyclic N-heterocycle. To efficiently synthesize this tricycle, polycyclization of
On the photoluminescence in triarylmethyl-centered mono-, di-, and multiradicals
Beilstein J. Org. Chem. 2025, 21, 964–998, doi:10.3762/bjoc.21.80
- mechanisms and reasons behind the fluorescence color and the fluorescence quantum yield and derive structure–optical property relationships. We will provide the reader with an overview of the perspectives and challenges of open-shell light-emitting radicals and discuss what to do to solve the remaining
- in Py2MTM is increased 3000-fold. The nuclear spin of the nitrogen in PyBTM and Py2MTM can couple with the radical electron spin, leading to EPR spectra with hyperfine structure [58]. Effectively, the substitution in ortho-position has strong electronic as well as steric effects, allowing to tune the
- extension of the Cz donor structure to benzocarbazole (BCz) and dibenzocarbazole (DbCz) follows the trend of the above described three-state model (see Figure 11). However, further extension to aza[7]helicenes also leads to contradiction with the model (cf. compounds 35 and 36 in Figure 8a and b). The ϕs of
Studies on the syntheses of β-carboline alkaloids brevicarine and brevicolline
Beilstein J. Org. Chem. 2025, 21, 955–963, doi:10.3762/bjoc.21.79
- , further investigation is needed to prove this observation. However, the mentioned alkaloids have high potential as medications. Based on the above, research on the total synthesis of these alkaloids and their closely related derivatives is crucial for further confirming their structure and for ensuring
- publications [19][23][24] confirmed the structure with IR and MS data, or by reactivity. Herein, we report the full set of assigned 1H and 13C NMR data for both the base and the dihydrochloride salt. In the course of our efforts devoted to elaborating a new and efficient synthesis of brevicarine (2), we
- catalyst, overreduced product 31, i.e., the tetrahydro derivative of racemic brevicolline ((±)-1) was obtained in 91% yield. Structure determination of 31 was supported by single-crystal X-ray diffraction, as well (Figure 2). Changing the catalyst [Pd(OH)2, Ru, Rh], did not alter the course of the reaction
Harnessing tethered nitreniums for diastereoselective amino-sulfonoxylation of alkenes
Beilstein J. Org. Chem. 2025, 21, 947–954, doi:10.3762/bjoc.21.78
- examples of amino-sulfonoxylations using tethered nitreniums. Putative reaction mechanism. (A) Scale-up and (B) applications. Optimization results. Structure–reactivity relationship with nitrenium tethers. Examination of sulfonic acid scope. Substrate scope exploration with an emphasis on stereocontrol and
Study of tribenzo[b,d,f]azepine as donor in D–A photocatalysts
Beilstein J. Org. Chem. 2025, 21, 935–944, doi:10.3762/bjoc.21.76
- of D–A structures makes them the ideal structures to further understand the structure–property relationship of D–A molecules for optimizing their photocatalytic performance by simpler modification of the different D–A subunits. In particular, D–A structures featuring sulfur-based acceptors and
- is a particular interest in the obtainment of organic molecules with well-balanced redox potentials in the excited state that can act as bimodal photocatalysts, facilitating their use in oxidative and reductive quenching cycles. In this sense, it is crucial to understand the molecule's structure
- –properties dependence to modulate its optical and photoredox properties [4]. For instance, molecules with donor–acceptor (D–A) structures, classically used as OLED emitters, have gained relevance by finding alternative applications in the field of photocatalysis [5]. In this type of structure, the electron
A convergent synthetic approach to the tetracyclic core framework of khayanolide-type limonoids
Beilstein J. Org. Chem. 2025, 21, 926–934, doi:10.3762/bjoc.21.75
- their total synthesis. Two synthetic studies were disclosed successively by Sarpong [27] and Jirgensons [28], both focusing on the construction of the unique methanoindene cage structure (A1A2B ring system). Building upon our previous syntheses of phragmalin-type limonoids [29], we herein disclose a
- 11 in the presence of AcOH by exposure to UV-light at 254 nm occurred exclusively to provide an inseparable mixture of 32 and 33 (Table 1, entry 5). Subsequent dehydration of the resultant mixture with SOCl2 and pyridine yielded separable enones 34 (51%) and 10 (9%) over two steps. The structure of
- ). Construction of α-iodoenone 13. Construction of aldehyde 14. Synthesis of the advanced intermediate 10 (in the X ray structure of 10 solvent molecule is omitted for clarity). Optimization of the interrupted Nazarov cyclization.a Supporting Information Deposition number 2406738 contains the supplementary
Silver(I) triflate-catalyzed post-Ugi synthesis of pyrazolodiazepines
Beilstein J. Org. Chem. 2025, 21, 915–925, doi:10.3762/bjoc.21.74
- trifluoromethyl and nitro groups. Furthermore, substrates 15m–o derived from aliphatic amines, also performed well, furnishing pyrazolodiazepines 16m–o in up to 89% yield. The structure of 16m, a representative compound of this series, was confirmed through single-crystal X-ray diffraction (scXRD) analysis
Recent advances in controllable/divergent synthesis
Beilstein J. Org. Chem. 2025, 21, 890–914, doi:10.3762/bjoc.21.73
- protoberberine and protonitidine alkaloids are characterized by an isoquinoline ring skeleton. An analysis of their molecular structures revealed that the two alkaloids share a basic structure, differing only in the junction of the B-ring. In 2021, Liu and Jiang designed new pyridyne precursors, which underwent
- discussion emphasizes structure–reactivity relationships and catalytic design principles that enable predictable access to distinct molecular architectures from shared synthetic intermediates. This review serves as a conceptualized platform for controllable/divergent synthesis, arousing more state-of-the-art
Dicarboxylate recognition based on ultracycle hosts through cooperative hydrogen bonding and anion–π interactions
Beilstein J. Org. Chem. 2025, 21, 884–889, doi:10.3762/bjoc.21.72
- binding sites to enhance anion binding [30]. The recognition capabilities of these ultracycles toward a range of dicarboxylates were successfully demonstrated. Results and Discussion Synthesis and structure The ultracycles B4aH, B5aH, and B6aH were synthesized following the previously reported procedure
- hydrogen bonding and anion–π interactions between the host and guest, we carried out geometry optimizations using M06-2X at the 6-31G(d) level of theory, taking the [B4aH·C72−] complex as a representative example [35][36]. The optimized structure, shown in Figure 3, reveals a 1:1 complex in which the
- interactions, the host undergoes conformational adjustments: the distance between the two submacrocycles increases, and the glycol chains adopt extended conformations compared to the structure shown in Figure 1. These results suggest that the experimentally observed strong binding capability and selectivity of
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